Add /contacts and /calendar pages; email signature settings; v1.1.12

- /contacts: standalone page with hybrid contact list (submissions + manual entry), inline edit, search, archive
- /calendar: monthly release scheduling calendar reading/writing podcast checklist episode dates
- /email settings: editable signature panel; signature persisted server-side and injected into outgoing emails
- Move contacts out of /admin panel (now links to /contacts route)
- Partial PATCH for contact submissions (name, notes, archived independently)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server.js

@@ -23,6 +23,7 @@ import {
   loadEpisodePlaysFromDisk,
   loadPodcastChecklistFromDisk,
   loadAnalyticsEventsFromDisk,
+  loadEmailSettingsFromDisk,
   createBackupSnapshot,
   refreshContentCaches,
   queueHitStatsWrite,
@@ -143,6 +144,7 @@ Promise.all([
   loadEpisodePlaysFromDisk(),
   loadPodcastChecklistFromDisk(),
   loadAnalyticsEventsFromDisk(),
+  loadEmailSettingsFromDisk(),
   refreshContentCaches(),
 ])
   .catch(err => {